A method and system for correcting defective pixels of a color image, which first performs an interpolation on a Bayer image captured by an image sensor to thus reconstruct red, green and blue (RGB) colors corresponding to each pixel and obtain an RGB image, then converts the RGB image from the RGB domain to a chroma domain, and finally uses neighboring pixel values to correct a respective defective pixel. Because a defective pixel can be distinct from the chroma domain easier than the RGB domain, it can accurately determine whether or not a pixel to be processed is defective.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for correcting defective pixels of a color image in a color image processing system, which detects and corrects defective pixels of a digital image, the method comprising the steps of: using a processor to perform the following steps: (A) receiving a pixel and its neighboring pixels of the digital image; (B) interpolating the pixel with red, green and blue colors; (C) producing a first chroma signal and a second chroma signal based on the red, green and blue colors of the pixel interpolated; (D) performing a filtering process on the first chroma signal and the second chroma signal to thus produce a third chroma signal and a fourth chroma signal; (E) determining the pixel as a defective pixel when the third or fourth chroma signal is smaller than a threshold; and (F) computing edge features of the pixel and neighboring pixels, and selecting pixel values from the neighboring pixels in accordance with the edge features for a correction operation of the defective pixel.
2. The method as claimed in claim 1 , wherein the first chroma signal is obtained by subtracting the green color of the pixel interpolated from the red color of the pixel interpolated.
3. The method as claimed in claim 1 , wherein the second chroma signal in the step (C) is obtained by subtracting the green color of the pixel interpolated from the blue color of the pixel interpolated.
4. The method as claimed in claim 1 , wherein the filtering process in the step (D) performs a median filtering process on the first chroma signal.
5. The method as claimed in claim 4 , wherein the filtering process in the step (D) performs a low pass filtering process on a signal produced after the median filtering process to accordingly produce a fifth chroma signal, and then subtracts the fifth chroma signal from the first chroma signal to thus produce the third chroma signal.
6. The method as claimed in claim 1 , wherein the filtering process in the step (D) performs a median filtering process on the second chroma signal.
7. The method as claimed in claim 6 , wherein the filtering process in the step (D) performs a low pass filtering process on a signal produced after the median filtering process to accordingly produce a sixth chroma signal, and then subtracts the sixth chroma signal from the second chroma signal to thus produce the fourth chroma signal.
8. The method as claimed in claim 1 , wherein the threshold in the step (D) is determined in accordance with a value of the green color of the pixel interpolated.
9. A system for correcting defective pixels of a color image, which detects and corrects defective pixels of a digital image, the system comprising: an interpolator, which receives a pixel and its neighboring pixels of the digital image and interpolates the pixel with red, green and blue colors; a chroma generator, which is connected to the interpolator, produces a first chroma signal and a second chroma signal based on the red, green and blue colors of the pixel interpolated; a defective pixel detector, which is connected to the chroma generator, filters the first chroma signal and the second chroma signal and produce a third chroma signal and a fourth chroma signal to thus produce a defective signal, which indicates the pixel received as a defective pixel, when the third chroma signal or fourth chroma signal is smaller than a threshold; and a defective pixel corrector, which is connected to the defective pixel detector, computes edge features of the pixel and neighboring pixels in accordance with the defective signal, and selects pixel values from the neighboring pixels in accordance with the edge features for a correction of the defective pixel.
10. The system as claimed in claim 9 , wherein the chroma generator further comprises a first subtractor to produce the first chroma signal by subtracting a value of the green color of the pixel interpolated from a value of the red color of the pixel interpolated.
11. The system as claimed in claim 9 , wherein the chroma generator further comprises a second subtractor to produce the second chroma signal by subtracting the green color of the pixel interpolated from the blue color of the pixel interpolated.
12. The system as claimed in claim 9 , wherein the defective pixel detector further comprises: a first median filter, which performs a first median filtering process on the first chroma signal; a first low pass filter, which is connected to the first median filter in order to perform a low pass filtering process on a signal produced by the first median filter to accordingly produce a fifth chroma signal; and a third subtractor, which is connected to the first low pass filter in order to subtract the fifth chroma signal from the first chroma signal to thus produce the third chroma signal.
13. The system as claimed in claim 12 , wherein the defective pixel detector further comprises: a second median filter, which performs a second median filtering process on the second chroma signal; a second low pass filter, which is connected to the second median filter performs a low pass filtering process on a signal produced by the second median filter to accordingly produce a sixth chroma signal; and a fourth subtractor, which is connected to the second low pass filter subtracts the sixth chroma signal from the second chroma signal to thus produce the fourth chroma signal.
14. The system as claimed in claim 13 , wherein the defective pixel detector further comprises: a lookup table , which is connected to the interpolator, produces the threshold in accordance with a value of the green color of the pixel interpolated, a first comparator, which is connected to the third subtractor and the lookup table, compares the third chroma signal with the threshold and produces the defective signal when the third chroma signal is greater than the threshold; and a second comparator, which is connected to the fourth subtractor and the lookup table, compares the fourth chroma signal with the threshold and produces the defective signal when the fourth chroma signal is greater than the threshold.
15. The system as claimed in claim 9 , wherein the defective pixel corrector, which is connected to the defective pixel detector and the interpolator, for computing edge features of the pixel and neighboring pixels which is outputted from the interpolator in accordance with the defective signal, and selecting pixel values from the neighboring pixels for a correction of the defective pixel in accordance with the edge features.
16. A system for correcting defective pixels of a color image, which detects and corrects defective pixels of a digital image, the system comprising: an interpolator, which receives a pixel and its neighboring pixels of the digital image and interpolates the pixel with red, green and blue colors; a chroma generator, which is connected to the interpolator, for producing a first chroma signal and a second chroma signal based on the red, green and blue colors of the pixel interpolated; a defective pixel detector, which is connected to the chroma generator, for filtering the first chroma signal and the second chroma signal and producing a third chroma signal and a fourth chroma signal to thus produce a defective signal, which indicates the pixel received as a defective pixel, when the third chroma signal or fourth chroma signal is smaller than a threshold; and a defective pixel corrector, which receives the pixel and neighboring pixels and is connected to the defective pixel detector, for computing edge features of the pixel and neighboring pixels in accordance with the defective signal, and selecting pixel values from the neighboring pixels for a correction of the defective pixel in accordance with the edge features.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 2, 2006
September 15, 2009
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